Liquid fuel burners



Oct. 25, 1966 H. E. JACKSON ETAL 3,280,883

LIQUID FUEL BURNERS Filed Feb. 25, 1965 2 Sheets-Sheet 1 16 l/vvewroks HHRow ERNESTJHCKSDN DOUGLHS g m/Mom) bEflN 771w, QalM M/ i Z0 ATTORNEYS Oct. 25, 1966 H. E. JACKSON ETAL 3,280,883

LIQUID FUEL BURNERS Filed Feb. 23, 1965 2 Sheets-Sheet 2 INVENTOKS HHROLD ERNEST JHC KsoN DOUGLFIS R YMUND DEHN 5) ATTORNEYS United States Patent 3,280,883 LIQUID FUEL BURNERS Harold E. Jackson, Plympton, Devon, and Douglas Raymond Dean, Plymouth, Devon, England, assignors to Tecalemit (Developments) Limited, Plymouth, Devon,

England Filed Feb. 23, 1965, Ser. No. 434,493 8 Claims. (Cl. 158-28) This invention relates to liquid fuel burners and it has for its principal object the provision of improvements in oil fuel burners, although it is also applicable to burners intended for use with other liquid fuels.

A further object of the invention is the provision of an oil or other liquid fuel burner which will operate at high efficiency with a blue flame and which will produce a low content of carbon monoxide in the waste products.

The invention, in one of its aspects, accordingly provides a liquid fuel burner comprising a combustion chamber having a supply passage opening into it and means including an atomising head and nozzle for injecting fuel and primary combustion air into the supply passage and through it into the combustion chamber in a direction to cause burning fuel and air to circulate in this chamber, which chamber includes at least one inlet for secondary air to complete combustion and an outlet for the discharge of burning gases, the arrangement being such that liquid fuel and primary air in a quantity insuffi cient for complete combustion can be injected into the supply passage at a speed suflicient to prevent combustion adjacent the nozzle.

The combustion chamber is preferably made of a generally circular cross-section and has the supply passage opening into it in a tangential direction. The outlet for burning gases from the chamber is advantageously through perforations formed in a plate, which plate may be in the form of a removable cover for the top of the combustion chamber.

The fuel and primary air are preferably injected into the supply passage at an acute angle to the axis of the latter, in a direction which is inclined towards the centre of the combustion chamber and which is preferably also inclined downwardly towards the bottom of the combustion chamber. Furthermore, a deflector plate is preferably provided within the combustion chamber, which plate extends inwardly in an arcuate direction from a point which is located adjacent the inner end of the supply passage and adjacent the outer wall of the combustion chamber, the inner end of this deflector plate being located at an intermediate point between the wall and the centre of the combustion chamber. The upper edge of the deflector plate may be and preferably is spaced from the top of the combustion chamber, to allow the passage of burning gases over it, this edge being preferably inclined downwardly from the outer towards the inner end of the plate.

The secondary air is preferably admitted and drawn into the combustion chamber through an inlet which projects into the interior of the chamber and which is itself of a tapered form having its larger end within the chamber.

Further features of the invention will become apparent from the following description of a preferred form of oil fuel burner which exemplifies the invention Reference will be made to the accompanying drawings, in which:

FIGURE 1 is a plan view of the burner, which is shown partly broken away and in section;

FIGURE 2 is a section taken on the line and in the direction indicated by the arrows ZZ in FIGURE 1.

3,280,883 Patented Oct. 25, 1966 "ice FIGURE 3 is a section taken on the same line but in a reverse direction, as indicated by the arrows YY in FIGURE 1;

FIGURE 4 is a section taken on the line and in the direction indicated by the arrows ZZ in FIGURE 1.

Referring to the drawings, the burner comprises an atomising head, indicated generally at 1, which is connected with a combustion chamber 2 by means of a base 3, which base, together with feet 4 mounted on the bottom of the chamber 2, supports the burner as a Whole.

The atomising head 1 comprises an electric motor 5 which drives a centrifugal fan 6 and an oil pump 7. These together inject oil and primary air into a supply passage 8 leading into the combustion chamber 2. The oil is injected into this passage 8 through an atomising nozzle 9, whilst primary air is discharged through a draught tube 10 which surrounds the nozzle 9 concentrically with the latter.

As will be seen from the drawing the supply passage 8 leads into the cylindrical combustion chamber 2 in a generally tangential direction, whilst the nozzle 9 and draught tube 10 are inclined both inwardly (relatively to the axis of the passage 8) towards the centre of the chamber 2 and downwardly towards the bottom thereof.

Furthermore, in order to direct the gases entering and circulating in the combustion chamber, a deflector plate or baffle 11 is provided within the chamber, which plate is of arcuate shape, when viewed in plan, and extends into the chamber 2 towards the centre of the latter from a point where the side of the supply passage 8 meets the peripheral wall of the chamber. As will be seen from FIGURE 3, the top of the deflector plate 11 is spaced from the top of the combustion chamber 2 and is inclined downwardly towards its inner end.

The combustion chamber 2 is provided with a pair of spark electrodes 12 to ignite the gases whilst it also includes an inlet 13 for secondary air, the construction and operation of which will be more fully described.

A cover 14, which is formed with perforations 15 over substantially its whole area, is fitted to the top of the chamber 2 and the burning gases are discharged through these perforations, where they form a blue flame.

During working the pump 7 delivers oil at a high pressure to the nozzle 9, where the oil is atomised by being forced through a small orifice in the nozzle. At the same time primary air is delivered from the fan 6 through the draught tube 10. This air and the atomised oil are discharged together through the passage 8 into the combustion chamber 2.

The parts are so designed that the primary air delivered by the fan 6, in relation to the oil delivered by the pump 7, is insuflicient to provide complete combustion of the oil. Furthermore, the oil and air are delivered at such a high velocity that the flame would be unstable if it were burning freely in the normal way. With the arrangement described, however, in which a reduced amount of primary air is introduced at high velocity to the atomised fuel leaving the nozzle 9, a very intimate mixture of the fuel and air can be obtained within the supply passage 8 while at the same time combustion near the nozzle 9 and within this passage is prevented.

Ignition of the burner is effected by the spark electrodes 12, which are connected to a high voltage means transformer (not shown). It is a feature of this burner that the ignition electrode can be mounted well clear of the main jet stream from the nozzle, so that they do not become over-heated during normal running of the burner, nor do they interfere with the flow of gases round the combustion chamber 2.

The discharge across theelectrodes 1 2 to ignite the burner has only to be maintained for a few seconds, after which the ignition is switched off.

The angle of the discharge from the nozzle 9 and draught tube 10 and the angle and shape of the deflector plate or baflle 11 are so -designedfthat the..oil and gases do not-strikethe-deflector plate toosquarelybut are de-. flected smoothly round the combustion chambenLIFun-ft thermore, by the time the jet ofzoil and air has reached the plate 11 it-has beenheated sufliciently by the. flame". for the oil not yet burnt-to become gasified, which .prevents droplets of oil from impinging" and'collecting' on the plate 11 As thestream of burning oilfand. air. circulates.roundf. the combustion chamber 2 it passes overland round the 15 secondary airinlet 13,Where it causes secondary. air'fto be drawn into the chamber; this secondary air. mixes with. the burning oil and primary air and causes true and com plete combustion to start.

Experiments have shownthat if the secondary air. is sim-ply allowed to enter through a;plain holein the bottom. of the combustion chamberlthe lower edge ofthe gas stream passing the secondary air inlet. will burn. too. fiercely, with the production .offlame noiser However, by bothraising and spreadingthesecondary air supply so125 that it meets and is distributed in .the'stream. of gases nearer the centre of the latter, the flame noise canbeverylv greatly. reduced .or even eliminated. Inthe .construction'. shown this is done by'makingthe secondaryair inlet in! the .form of a frusto-conical tube the upper end of which isthe'largen'asshown. a r1- t The amount of secondary air which is drawn in can be controlled. by suitable designingeof. the siz'e of thehole- 16in the bottom of the chamber 2 through which the secondary air enters- I a ,35

The conical shape. of the-secondaryiair. inlet..13l.h'as been found to give a good spreading of the secondary air: entering the combustion chamber .2, without uttering .tooT much resistance to the smooth progress of the burning" gases round the chamber.

The burning gases circulate round the combustion. chamber. 2, after leaving the secondary air inlet 13, but they will now tend to rise towards the. top of the chamber where they arepartly reduced by theeflectof theperforationsuin the cover 14. Small amounts of the burning gases escape throughtheindividual perforations, the re mainder of .the gases continuingto circulatejustbelow the cover plate '14 where some of.them.may.pass over the passage 8 anddeflector plate .11, the :result being; the formation of a. continuous blanket of burning gases just belowthecoverplatel l.v 1.. :1 n.

-All .thesegases .will eventually bedischarged through the. perforations 15, where they willacomeliinto contact. with external air, producing a blue flame with very good combustion characteristics t If desired,ua-.flame spreader, suchas that indicated. at. 17 'in FIGURE 3, maybe fittedover the top of the cover"v 14. 'It has been found that such.a flame. spreader like any. olpstructions outside. thecombustion chamber has little effect on the flame characteristics;

The. burner which has been described. may be made of. any suitable mate1ials. I .The perforatedcover.plate l4. must .be made. of a.flame-resistant:material, suchuasta heat-resistant stainless steel, butother and .Chcap'er. materials can be used f or. .the remainder of the combustion chamber 2. The walls of the latter could, for example, be made of mild steel sheet or of cast iron.

We claim:

1 A liquid fuel burner. comprisinga, combustion 70 chamber haying asupply passageopeningIinto it. and means including an atomizinghead and II ZZLQsfOIiII. jecting fuel and primary combustion ,air to said supply, passage and through it into said combustion chamber in a direction to cause burning fuel and air to circulate in 75 id. hamber whi chambe in lude? a le st inlet for secondary air to complete combustion and an outlet concavejside' thereofltoward'the inside of said combus- -tion,cl 'iamber and extending from a point adjacentthe inher end of said supply'pa's'sage and adjacent the outer wall of said combustion chamber and having its inner end spaced between said: wall and the center of said chamber, the upper edge of said deflector plate being spaced from .the top of the combustion chamber and inclined downwardly from itsouter end to its inner end, said inlet for secondary air projectinginto the interior of the combustion chamberand being tapered having its larger, end

within said vchamberand being positioned tangentially spaced fro rn the end of said deflectorplate so that the stream of gases;is directed by said deflector plate over and u dsa d scon r in l t...

..;2 A, liquid fuel burner 5 comprising a combustion chamber; of generally circular cross-section having a suplypassage opening into it in a generally tangential direction, and means including an 'atomizing head and nozzleforinjectingfueland primary combustion air into I the supply passageand through it into the combustion chamber to cause burning fuel and airto circulate in this ch amber,; wherein the combustion chamberisprovid'ed with a deflectorlin the formof a plate which extends inwardly inan arcuate direction, the'convex side of said plate, being positioned outwardly "toward the wall of said combustion chamber, said deflector. plate extendin g from afpointfadjacent.the'inner tangential end ofsaid supply passage generally tangentially and adjacent the outerwall of the combustion chamberand which 'has its inner end spaced' betwee'nfthis wall and the center of the chamber.

. 3. A' burner as: set f forth in'claim 2 above wherein 0 the upper. edge.ofthedeflectorplate is spacedfrom the top' of the combustion'chamber .and is inclined down- Wardlyj from its out'enend' towards its inner end.

4. A burner according to'clai'm'3 abovewhe'rein the outlets for the burning gases arenprovided. by perforationsin acover plate'whichis fitted to the top of the combustion Chamber.

5. A liquid fuel burner comprising a combustion chamber of generally circular cross-section having a supply ,passage opening'into it in. a generally tangential direction, an atomizing head andfnozzle for injecting fuel and primary combustion air into the supply passage and through itiinto the combustion chamber to cause. burning fuel and air' to circulatein'this chamber, said atomizing head and no'zzle'being at an -acuteangle to the axisof said supply passage'in a direction whichfis inclined'towa'rd the center of the, combustion chamber, said co'mbustio'n chamber being provided with aldeflecto'r for deflecting thebur ningflfueland airinwardly from the'wall of the chamber, at least one inlet for admitting secondary air 0 into the'ch'ambe'r and a to'p having a plurality of outlets through it for the discharge of burning gases'fromthe chamber. I

6. burner according to claim S above wherein said atomlz ng head and nozzlepare further inclined down wardly toward the bottom or the passage and towardthe bottom of said combustion chamber.

7. A liquid fuel burner comprising a combustion" chamber of. generally circular cross-section having a supply, passage opening into it in a'gener'ally tangential' direction, and means including an atomiz'in'g head and nozzle for injectingfuel and primary combustion air into the. supply passage and through it into the combustion chamber to cause burning'fuel and air to circulate in this 5 6 1y from the Wall of the chamber, at least one inlet for References Cited by the Examiner admitting secondary air into the chamber and projecting UNITED STATES PATENTS into the interior of the combustion chamber and being of tapered form having its larger end Within the chamber 781,922 2/1905 Thomson" above the bottom of said chamber, and a top having a 5 1,699,732 1/1929 Balmat' 1 2 plurality of outlets through it for the discharge of burn- 1910761 5/1933 Grant et 158 8 ing gases from the chamber 2,408,865 10/ 9 M y 15 8 8. A burner according to claim 7 wherein the second- FOREIGN PATENTS ary air inlet is located at a point which is spaced from 59,501 7/1925 France and which is preferably substantially diametrically op- 10 posite the supply passage. JAMES W. WESTHAVER, Primary Examiner. 

1. A LIQUID FUEL BURNER COMPRISING A COMBUSTION CHAMBER HAVING A SUPPLY PASSAGE OPENING INTO IT AND MEANS INCLUDING AN ATOMIZING HEAD AND NOZZLE FOR INJECTING FUEL AND PRIMARY COMBUSTION AIR TO SAID SUPPLY PASSAGE AND THROUGH IT INTO SAID COMBUSTION CHAMBER IN A DIRECTION TO CAUSE BURNING FUEL AND AIR TO CIRCULATE IN SAID CHAMBER, WHICH CHAMBER INCLUDES AT LEAST ONE INLET FOR SECONDARY AIR TO COMPLETE COMBUSTION AND AN OUTLET FOR THE DISCHARGE OF BURNING GAS SUCH THAT LIQUID FUEL AND PRIMARY AIR IN A QUANTITY INSUFFICIENT FOR COMPLETE COMBUSTION CAN BE INJECTED INTO SAID SUPPLY PASSAGE AT A SPEED SUFFICIENT TO PREVENT COMBUSTION ADJACENT SAID NOZZLE, AND A DEFLECTOR PLATE WITHIN SAID COMBUSTION CHAMBER EXTENDING INWARDLY IN AN ARCUATE DIRECTION WITH THE CONCAVE SIDE THEREOF TOWARD THE INSIDE OF SAID COMBUSTION CHAMBER AND EXTENDING FROM A POINT ADJACENT THE INNER END OF SAID SUPPLY PASSAGE AND ADJACENT THE OUTER WALL OF SAID COMBUSTION CHAMBER AND HAVING ITS INNER END SPACED BETWEEN SAID WALL AND THE CENTER OF SAID CHAMBER, THE UPPER EDGE OF SAID DEFLECTOR PLATE BEING SPACED FROM THE TOP OF THE COMBUSTION CHAMBER AND INCLINED DOWNWARDLY FROM ITS OUTER END TO ITS INNER END, SAID INLET FOR SECONDARY AIR PROJECTING INTO THE INTERIOR OF THE COMBUSTION CHAMBER AND BEING TAPERED HAVING ITS LARGER END WITHIN SAID CHAMBER AND BEING POSITIONED TANGENTIALLY SPACED FROM THE END OF SAID DEFLECTOR PLATE SO THAT THE STREAM OF GASES IS DIRECTED BY SAID DEFLECTOR PLATE OVER AND AROUND SAID SECONDARY AIR INLET. 